2012/12/17 A.Pirard.Papou <[email protected]> > A level is an altitude. A layer is a drawing opacity. Although OSM > does not tag for the renderer, it uses the tag *layer=**. It defines * > layer* as the relative "position" (is that "altitude"?) >
no, it is not altitude (height over ground), it is the relative position (relative to other objects at the same spot). > . In fact, the only effect of assigning a layer is that upper layer > objects hide lower layer ones (it's not a "mind your step" warning ;-)) > it is a way to describe in the database which object is above which or whether they are at the same level. > It's interesting to keep all the rails in the same layer to avoid splits > and layer =+1 may be needed for them to show at some places. My reaction > would be that the person having cared to explicitly set the level might > have had something on his mind. > The best way to know what he had in mind would be to write to this person and ask. As tram rails are (usually) on the same layer/level as the road itself I'd consider it wrong to have them on different layers. I have traced lengths of streams > > - stream as a constant layer=-2 way, uninterrupted end to end (even if > they "don't look so deep"), > - roads are at level 0 > - and bridges and culverts at level -1, in the manner mentioned above. > > very strange way of mapping IMHO, how did you come to this idea? Is there a page in the wiki which encourages this style? cheers, Martin
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